7. Project Summary/Abstract Despite the availability of prophylactic vaccines against HPV, modest increases in vaccination coverage among adolescents has been reported. In Puerto Rico (PR), where disparities in incidence, mortality, and survival of HPV-related cancers have been extensively documented, vaccination rates are low. The PR government recently enacted a policy to require HPV vaccination for all adolescents' ages 11-12 years who enroll in schools, beginning the next academic year (2018-2019). PR became the 5th US state or territory to adopt an HPV vaccine school-entry policy. Taking into account this important public policy implementation, the proposed study aims to examine geographic variation in the dissemination and implementation of HPV vaccine policies across US states and territories, while taking advantage of the timely opportunity to study the implementation and outcomes of the new school-entry HPV policy in PR in depth. This study will use a multi-method approach to analyze survey data, immunization registry data, and qualitative data using a combination of qualitative, correlational, comparative case study, multilevel analysis and natural experiment designs. Additionally, and in collaboration with our local and national partners, the study findings and recommendations will be disseminated back to stakeholders and decision makers to inform the ongoing evolution of the policy implementation in PR and other states with existing policies, and to inform states/territories that are considering adopting a new HPV vaccine school entry policy. Our research team is uniquely positioned to be able to carry this important and time-sensitive study given our long track record and existing collaborations with local and national academic partners and coalitions focusing on HPV vaccination. If granted, this project will serve to inform other states and territories considering HPV immunization policies and future implementation research on these policies. PHS 398/2590 (Rev. 06/09) Project Summary/Abstract Continuation Format Page